3D printable Visco fuse machine

[MrB]

They sell similar product at any home improvement / building stores here in Sweden, and call it anything like asphalt glue, asphalt primer, and asphalt sealer. They are all slightly different from one and other, but bottom line is it's a bitumen compound with different amounts, and different kinds of solvents.

 

Volume, anywhere from 0.3L and up, depending on the specific product. So it "should" be available for the fixer in UK as well. I hope.

[lloyd]

FWIW, what's used on fuse has NO solvents. They'd be absorbed by and carry bitumen into the powder core -- which is a definite "no-no"!

 

You need 'straight' tar. If it needs any modification at all, it's usually to stiffen it further with some Gilsonite.

 

A term used here for the stiffest roofing tar is "high pitch tar". That does not refer to the 'pitch content', but rather, the pitch of the roof on which it's intended to be used. I use high pitch tar, and still have needed to harden it a bit for our hotter weather.

 

Lloyd

[Simoski]

OK, so I printed a 50 mesh screen and began screening. I'm sure with the smaller grains and the larger die nozzles the fuse will flow. Although I still need to design and print something to handle the guide threads...

 

 

 

[Simoski]

I used small amounts of it to temper mine for 1/4" military fuse.

 

Proper!

[Simoski]

I just used a filter from a washing machine because that was what i had and that worked great.

What do you mean by this old chap? Did you get something out of a washing machine that can harden tar?

[Simoski]

Arthur/ LLoyd / MrB / Svimmer what about a paint as a waterproof coating, Maybe a polyurethane based one?

[lloyd]

Sim,

There are a few old-fashioned blasting fuses that were 'semi-waterproofed' with an outside overcoat of a sort of 'paint' that used beeswax as the vehicle. It was heavily-pigmented, and really didn't feel waxy, but made the fuse pretty-darned resistant to water.

 

Almost every method used to waterproof fuse employs a coating that does not require drying -- which can simply be applied by melting and re-solidifying. That, due to the LOOOONNNGGGG runs and drying tunnels that would be required in a varnish or paint application. Even one of the fuses I made required about 75' of heated drying run for the water-based 'anti-fray' coating that was applied after the final wrap was on the fuse.

 

If a varnish or paint were used, it would have to be selected for drying time and temp, for 'dry flexibillty', and for its resistance to being absorbed by (and thus adulterating) the core of the fuse.

 

These days, nearly every waterproof fuse is made with an extruded plastic outer jacket. That solves all the problems nicely, at the expense of a VERY high start-up cost for equipment.

 

Lloyd

[Baldor]

What do you mean by this old chap? Did you get something out of a washing machine that can harden tar?

As a sieve. You could try also to find a laundry dryer filter.

[Svimmer]

What do you mean by this old chap? Did you get something out of a washing machine that can harden tar?

No but to granulate the powder so it would flow nicely !

[lloyd]

Sim,

Keep in mind that commercial fuse powder is 'corned'. The particles, although somewhat irregular in shape, are closely-sized, and approximately the same dimensions in all axes. Home-made 'screen granulated' power is VERY irregular in shape. Those often long, irregular particles can tend to interlock when attempting to get them to flow.

 

Your choice of a finer screen is a good start, but you may also have to add 'active agitation' to the power hopper (sorry, if you did already, I didn't remember). Even mine had it (for corned powder), in the form of a stirring rod that circulated around the periphery of the hopper.

 

Lloyd

[Simoski]

As a sieve. You could try also to find a laundry dryer filter.

Check that!

 

Thanks I thought maybe laundry powder will help harden tar... : ) lol

[Simoski]

Sim,

Keep in mind that commercial fuse powder is 'corned'. The particles, although somewhat irregular in shape, are closely-sized, and approximately the same dimensions in all axes. Home-made 'screen granulated' power is VERY irregular in shape. Those often long, irregular particles can tend to interlock when attempting to get them to flow.

 

Your choice of a finer screen is a good start, but you may also have to add 'active agitation' to the power hopper (sorry, if you did already, I didn't remember). Even mine had it (for corned powder), in the form of a stirring rod that circulated around the periphery of the hopper.

 

Lloyd

Will guide threads be insufficient?

[lloyd]

Sim,

I had two 'guide threads' on my commercial machine. Even using commercial fuse powder, it still required a stirring mechanism.

 

Threads (by themselves) just tend to 'tunnel' in the continuously more-compacting mass of powder, until the mass doesn't move, and the tunnels are just a thread moving through air.

 

Lloyd

[Svimmer]

I havent had any problems at all to get the powder flowing when using the powder i granulate with the filter.

[lloyd]

Well, Stix,

Admittedly, I had a powder funnel that was quite a lot larger in capacity than what you guys are working with on a Visco machine. Mine held just shy of two pounds of powder, and the powder column was about 11" tall (including the funnel depth at the bottom).

 

Gravity was my enemy there. You guys may have better luck with the right classification of powder.

 

Lloyd

Edited May 22, 2018 by lloyd

[Simoski]

I will try again this weekend, hopefully by then I'll have the guide thread assembly designed and printed.

 

I saw these fuse comps by Spitfire made in 2015, what do you make of them...

 

 

white falling leaves fuse:

 

KNO3................50

Alu dark............30

sulfur................20

 

(0.5 cm/sec)

 

easy safety fuse:

 

KClO4.............70

Willow C..........25

 

(about 0.8 cm/sec)

 

add +5% fine flake Ti for silver falling leaves fuse.

 

''aggressive'' hot safety fuse:

 

KClO4.....................70

Pot. benzoate.........30

dark al.................... 2

sulfur.......................2

 

(1 cm/sec)

 

add 5% - 7% fine flake Ti for flying fish fuse. Use short lengths. They ''swim'' a lot.

 

Another safety fuse:

 

KClO4.........................75

C willow......................10

Pot. benzoate.............10

 

(1 cm/sec)

 

Delay fuse (rather fast):

 

Fine grained BP..........75%

Powder willow BP........15%

70/30 KClO4/C.............10%

 

(about 1.5 - 2.5 cm/sec)

Edited May 24, 2018 by Simoski

[lloyd]

Eh... Sim, I think I'd leave those alone until I could make good fuse with more-conventional black powder -- typically slightly oxidizer-poor and sulfur-rich.

 

Every one of those except the white falling leaves is basically flash powder or H3, both of which are considerably more explosive and more dangerous than BP.

 

When you get the machine dialed-in, and are certain of the consistency of fuse it creates, then it might be fun to fool with more exotic formulae. But like everything in life, pyro things tend go better when you approach experiments incrementally, rather than in great leaps that skip many 'basics'.

 

Lloyd

Edited May 24, 2018 by lloyd

[Simoski]

Yeah lets just get some working fuse first Sir.

[MrB]

I admit. I would probably run sugar in the machine just to get everything working, and dialed in. Might be messy to granulate, or powder, and clean up after testing, but at least it's not a fire hazard.

[Mumbles]

BP grains are tumbled with a small amount of graphite to improve the flow properties (amongst other reasons) for reloading. Do you think it would interfere with fuse making?

[Arthur]

In the scheme of naming the f's are fineness and the a is for granulated powder and the g is for graphite glazed. Does any literature say whether glazed or plain powder was used in history?

[lloyd]

Arthur, those are 'said' to be the meanings, but they are not.

 

'A' powder (capital 'A') is blasting powder. 'g' powder (lower-case 'g') is shooting powder. Not all 'g' powders are graphite-glazed.

 

The story has it that when Dutch traders were plying the African trade, the Africans thought more-highly of polished powder than of dull-looking, so they began to graphite-glaze for that market. But most powder sold then and much even now is not graphited, merely 'tumble polished'.

 

The two types of powder come in two entirely-different grain-size regimes, and conventionally are also named according to two different methods, so as not to be easily confused.

 

Blasting powders usually are named by an arabic numeral, followed by uppercase "FA". So "2FA, 4FA", etc.

Shooting powders are usually named by a number of upper or lower-case Fs, followed by a lower-case 'g'. So, FFFg or fffg.

 

'Hope that helps.

 

Lloyd

[WSM]

I admit. I would probably run sugar in the machine just to get everything working, and dialed in. Might be messy to granulate, or powder, and clean up after testing, but at least it's not a fire hazard.

 

Or, you could run it with 80 mesh charcoal to see how it works. If it's too light and fluffy to replicate BP, add powdered clay to the charcoal and try that.

 

I'm guessing this will work without gumming up the system.

 

Good luck.

 

WSM

Edited October 7, 2018 by WSM

[FlipperFuego]

Super interesting thread, thanks fro sharing! http://freeimagehost.info/i/SmQTeHNsQ9.png

[markx]

Using a "surrogate" filler to tune in the machine might not be very successful.....at least concerning the parameters of the actual fuse (uniformity, appearance, dimensions, etc.). It is ok to check the functionality of machine related parameters though. Wether everything runs smooth and reliably from the mechanical/electrical side.

I've messed around with fuse making for quite a while and from the little gathered experience I can tell that changing the formulation and especially the preparation process for the formulation can have immence impact on how the machine and the final product perform. So there really seems to be no "fit all" type of tune for a visco machine. Usually making a change to the composition or the preparation procedure of the filler material shall trigger the need to also make adjustments to the machine (changing the speeds and ratios of gearing, number or type of threads, tension of threads) to achieve the best possible outcome.

Hence using a surrogate filling is likely going to tune your setup to produce the respective surrogate fuse....but assuming the final composition is close enough in density, granulation and geometry of the particles, one may end up with a more or less functional result

Also a word of warning regarding granulated filler compositions: they tend to self seggregate in the funnel if the particle size distribution is not uniform. The coarsest particles (agglomerates e.g. ) tend to gather at the top of the feed funnel and exit last into the fuse. Hence the length of fuse produced from nonuniformly sized particles tends to have a systematic increase of filler particle size along it's length from the finest filler at the beginning and ending with the largest "lumps" at the tail portion. Accordingly the burning speed shall have a systematic growth along the length of the fuse with the fastest part being the tail portion of the produced fuse that contains the coarsest filler. This difference in burn speed can be monstrous....I've had batches where the nose end of the fuse burns at expected rate and the tail part basically explodes instantaneously along the length. So I've accustomed myself to test from the nose and tail part of every produced bundle to see if there is a detectable difference in burn speed and immediately discard the faster burning tail portions. No good to leave lying around to forget about their flaw and then end up with an unpleasant surprise.